Transmission Dose Estimation Algorithm for in Vivo Dosimetry


Purpose : Measurement of transmission dose is useful for in vivo dosimetry of QA purpose. The objective of this study is to develop an algorithm for estimation of tumor dose using measured transmission dose for open radiation field. Materials and Methods : Transmission dose was measured with various Field Size (FS), phantom Thickness (Tp), and Phantom Chamber Distance (PCD) with a acrylic phantom for 6 MV and 10 MV X-ray. Source to Chamber Distance (SCD) was set to 150 cm. Measurement was conducted with a 0.6 cc Farmer type ion chamber. Using measured data and regression analysis, an algorithm was developed for estimation of expected reading of transmission dose. Accuracy of the algorithm was tested with flat solid phantom with various settings. Results: The algorithm consisted of quadratic function of log(A/P) (where A/P is area-perimeter ratio) and tertiary function of PCD. The algorithm could estimate dose with very high accuracy for open square field, with errors within ±0.5%. For elongated radiation field, the errors were limited to ±1.0%. Conclusion : The developed algorithm can accurately estimate the transmission dose in open radiation fields with various treatment settings


Nuclear Engineering and Radiation Science

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Article - Journal

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© 2002 Korean Association for Radiation Protection, All rights reserved.

Publication Date

01 Jan 2002

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